One of several flowers surrounding chap’s about to burst open (7)
I believe the answer is:
dehisce
'burst open' is the definition.
(to dehisce is to burst open)
'one of several flowers surrounding chap's about' is the wordplay.
'one of several flowers' becomes 'Dee' (name of several rivers, things which 'flow').
'surrounding' is an insertion indicator.
'chap's' becomes 'his' (possessive pronoun for a male or 'chap').
'about' becomes 'c' (abbreviation for 'circa').
'his'+'c'='hisc'
'dee' placed around 'hisc' is 'DEHISCE'.
'to' acts as a link.
(Other definitions for dehisce that I've seen before include "Burst open, ejecting seeds" , "Gape" , "rupture" , "Seeds burst from pod" .)