People offer me more French coins at auction — not a shilling — with both hands (12)
I believe the answer is:
ambidextrous
'with both hands' is the definition.
(ambidextrous means able to use either hand well)
'people offer me more french coins at auction not a shilling' is the wordplay.
I cannot really see how this works, but
'offer' could be 'bid' (synonyms) and 'bid' is present in the answer.
'me' could be 'us' ('us' can mean 'me' in some dialects) and 'us' is present in the answer.
'more' could be 'm' and 'm' is present in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'a' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for ambidextrous that I've seen before include "Highly adept" , "Both right- and left-handed" , "Good with either hand" , "Able to use either hand equally well" , "Able to use both hands equally well" .)