Pimp's beginning to exploit her virtue — however, he may not succeed (4,11)

I believe the answer is:

heir presumptive

'he may not succeed' is the definition.
(one might be replaced before they can succeed)

'pimp's beginning to exploit her virtue however' is the wordplay.
'beginning to' indicates taking the first letters.
'however' indicates anagramming the letters.
The first letter of 'exploit' is 'e'.
'pimps'+'e'+'her'+'virtue'='pimpsehervirtue'
'pimpsehervirtue' with letters rearranged gives 'HEIR-PRESUMPTIVE'.

I've seen this clue in The Guardian.

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