Transfix victim, pal entrenched inside (6)
I believe the answer is:
impale
'transfix' is the definition.
('impale' can be a synonym of 'transfix')
'victim pal entrenched inside' is the wordplay.
'inside' says the answer is hidden in the clue.
'IMPALE' is hidden within 'victim pal entrenched'.
(Other definitions for impale that I've seen before include "Transfix, pierce (with a sharp instrument)" , "Pierce through as with sharp stick" , "spit!" , "Pierce with lance etc" , "go through with it" .)