Immature depiction of everyone in Jersey, say? (6)
I believe the answer is:
callow
'immature' is the definition.
('callow' can be similar in meaning to 'immature')
'everyone in jersey say?' is the wordplay.
'everyone' becomes 'all' (I've seen this before).
'in' is an insertion indicator.
'jersey say?' becomes 'cow' (Jersey cow is an example).
'all' going into 'cow' is 'CALLOW'.
'depiction of' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
(Other definitions for callow that I've seen before include "23 [BRIGHTONIAN] actor" , "Immature and inexperienced, as youth often is" , "Jejune" , "Immature and inexperienced, like youth" , "Inexperienced or unsophisticated, as a youth say" .)