Sweetbrier, for instance, with insect in occupation (9)
I believe the answer is:
eglantine
'sweetbrier' is the definition.
(synonyms)
'for instance with insect in occupation' is the wordplay.
'for instance' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'with' says to put letters next to each other.
'insect' becomes 'ant' (ant is a kind of insect).
'in' means one lot of letters goes inside another.
'occupation' becomes 'line' (line can mean someone's occupation or industry).
'ant' placed inside 'line' is 'lantine'.
'eg'+'lantine'='EGLANTINE'
(Other definitions for eglantine that I've seen before include "Inelegant (anag.); wild rose" , "Inelegant sort of sweet-brier" , "Strangely inelegant scented plant" , "Inelegant (anag) - plant" , "Milton's honeysuckle" .)