It's possibly blooming nice prince? (5,7)
I believe the answer is:
sweet william
'it's possibly blooming' is the definition.
(sweet william is a type of flower)
'nice prince?' is the wordplay.
'nice' becomes 'sweet' (both can mean agreeable or pleasant).
'prince?' becomes 'William' (Prince William).
'sweet'+'william'='SWEET-WILLIAM'
(Other definitions for sweet william that I've seen before include "bloomer" , "Eurasian plant with fragrant flowers" , "Flower (nice boy!)" , "Garden pink -- Willie wet Sam (anag)" , "Flowering plant - Prince at sixteen?" .)