Perhaps dog at college a bloomer (7)
I believe the answer is:
petunia
'bloomer' is the definition.
(I know that petunia is a type of bloomer)
'perhaps dog at college a' is the wordplay.
'perhaps dog' becomes 'pet' (dogs are often kept as pets).
'at' says to put letters next to each other.
'college' becomes 'uni' (short for university).
'pet'+'uni'+'a'='PETUNIA'
(Other definitions for petunia that I've seen before include "Plant cultivated for its white, pink, blue or purple funnel-shaped flowers" , "Flower - tuna pie (anag)" , "Auntie foolishly made under pressure" , "Flower much used in hanging baskets" , "Colourful" .)