Such a net may become loose (8)
I believe the answer is:
unchaste
'loose' is the definition.
(similar in meaning)
'such a net may become' is the wordplay.
'may become' is an anagram indicator.
'such'+'a'+'net'='suchanet'
'suchanet' with letters rearranged gives 'UNCHASTE'.
(Other definitions for unchaste that I've seen before include "Enjoying sex" , "libertine" , "Impure" , "Sexually immodest" , "Dissolute" .)