Formal uniform lightened at the front with a flower (7)
I believe the answer is:
primula
'flower' is the definition.
(I know that Primula is a type of flower)
'formal uniform lightened at the front' is the wordplay.
'formal' becomes 'prim' (I've seen this in other clues).
'the front' indicates taking the first letters.
The first letters of 'uniform lightened at' is 'ula'.
'prim'+'ula'='PRIMULA'
'with a' is the link.
(Other definitions for primula that I've seen before include "Cowslip relative" , "Spring flower" , "Air plum, oddly, from this plant" , "Plant such as cowslip" , "Cowslip genus" .)