Bond cuddling girls, sex not entirely judged fairly (4-8)

'judged fairly' is the definition.
(judged in a fair way)

'bond cuddling girls sex not entirely' is the wordplay.
'bond' becomes 'weld' (I've seen this before).
'cuddling' is an insertion indicator.
'girls' becomes 'lasses' (lass can informally mean a girl).
'not entirely' means to remove the last letter.
'lasses'+'sex'='lassessex'
'lassessex' with its last letter taken away is 'lassesse'.
'weld' enclosing 'lassesse' is 'WELL-ASSESSED'.