Flower offered by son in bovine insolence (7)
I believe the answer is:
cowslip
'flower' is the definition.
(thesaurus)
'son in bovine insolence' is the wordplay.
'son' becomes 's'.
'in' indicates putting letters inside.
'bovine' becomes 'cow' (cow is a kind of bovine).
'insolence' becomes 'lip' (I've seen this before).
'cow'+'lip'='cowlip'
's' inserted inside 'cowlip' is 'COWSLIP'.
'offered by' acts as a link.
(Other definitions for cowslip that I've seen before include "Wild yellow primula" , "Yellow spring flower" , "bloomer" , "Early spring flower" , "Yellow flower for unsteady bovine?" .)