Perhaps monitor student magician removing head (6)
I believe the answer is:
lizard
'perhaps monitor' is the definition.
(I know that monitor is a type of lizard)
'student magician removing head' is the wordplay.
'student' becomes 'L' (as in L-plates for learner drivers).
'magician' becomes 'wizard' (synonyms).
'removing head' means to remove the first letter.
'wizard' with its initial letter taken away is 'izard'.
'l'+'izard'='LIZARD'
(Other definitions for lizard that I've seen before include "part of Cornish coast" , "Four-legged reptile" , "Reptile with four legs and long tail" , "The most Southerly point of England" , "Kind of reptile - chameleon is one" .)