nakha 'nail' in sanskrit

I've question on the Sanskrit word for nakha 'nail':
How do the IE lingists explain 'kh' in 'nakha'?

Monier-Williams dictionary gives:
nakha

Meaning m. n. (fr. %{nagh} [?] cf. %{naghamAra} ; prob. not fr.
%{na} + %{kha} in spite of Pa1n2. 6-3 , 75 ; ifc. f. %{I})
a finger-nail , toe-nail , claw , talon , the spur of a cock RV.
&c. &c. (%{-khAni-kR} , or %{klRp} , to cut the nails Kaus3. Mn.) ;
= 20 Su1ryas. ; n. and (%{I}) f. Unguis Odoratus VarBr2S. Hcat. ;
m. part , portion. [Cf. Gk. $ , stem $ ; Lat. &162290[524 ,3]
{unguis} ; Lit. {na4gas} ; Slav. {nogu8ti8} ; Angl. Sax. {naegel} ;
Eng. {nail} ; Germ. {Nagel}.]

Are there examples where IE words' -g- change to -kh- in Sanskrit?

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Tamil, a Dravidian language, uses 'nakam' for nail.
There are examples where word-initial n- is lost in Dravidian.
nuntu/untu 'to push', nIr 'water' & Iram 'wetness' etc. etc.
nuntA/nontA-viLakku 'perpetual lamp granted to temples' in old
tamil inscriptions.

nuntAviLakku > nantAviLakku (both have very old attestations).
The tamil nakam is possibly:
nukam 'yoke' (in a plough or cart) > nakam 'nail'.
(because like nakam 'nail', yoke sits on a bullock).
nakam-nukam relations can be seen in another way:
With initial loss of n-, compare ukam 'yoke' with ukir 'nail'.

The relation between nakam (tamil) and nakha (sanskrit)
is interesting.

Regards,
N. Ganesan