Love to form a bond that's outstanding (4)
I believe the answer is:
owed
'outstanding' is the definition.
(as in an outstanding debt)
'love to form a bond' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'to form a bond' becomes 'wed' (as in wedding things together).
'o'+'wed'='OWED'
'that's' is the link.
(Other definitions for owed that I've seen before include "Outstanding" , "to be paid" , "Had an obligation to pay" , "In debt to" , "(Sum) due for payment" .)