Further contribution to Royal Society (4)
I believe the answer is:
also
'further' is the definition.
(I've seen this before)
'contribution to royal society' is the wordplay.
'contribution to' says the answer is hidden in the clue.
'ALSO' is hidden within 'royal society'.
(Other definitions for also that I've seen before include "What's more" , "As well, in addition" , "item's rarely used now for this" , "on top" , "To boot" .)