Watch out for the insect going around raw back (6)
I believe the answer is:
beware
'watch out for' is the definition.
(I've seen this before)
'insect going around raw back' is the wordplay.
'insect' becomes 'bee' (bee is a type of insect).
'going around' means one lot of letters goes inside another.
'back' shows that the letters should be reversed in order.
'raw' back-to-front is 'war'.
'bee' placed around 'war' is 'BEWARE'.
'the' acts as a link.
(Other definitions for beware that I've seen before include "Look out, take care" , "Word of warning" , "Have caution, be on guard" , "See 18" , "Wee bra (anag)" .)