Competed with a girl and boy (4)
I believe the answer is:
vied
'competed' is the definition.
('vie' can be a synonym of 'compete')
'a girl and boy' is the wordplay.
'a girl' becomes 'Vi' (short for Violet).
'and' means one lot of letters go next to another.
'boy' becomes 'ed' (short for edward).
'vi'+'ed'='VIED'
'with' acts as a link.
(Other definitions for vied that I've seen before include "Contested in dive" , "'Competed, contended (4)'" , "Competed in dive" .)