Mad attempt to join Royal Academy? (5)
I believe the answer is:
rabid
'mad' is the definition.
(I've seen this in another clue)
'attempt to join royal academy?' is the wordplay.
'attempt' becomes 'bid' (bid is a kind of attempt).
'to join' is a charade indicator (letters next to each other).
'royal academy?' becomes 'RA'.
'bid' after 'ra' is 'RABID'.
(Other definitions for rabid that I've seen before include "Raging (having been bitten by a dog?)" , "Fanatical, infected" , "Ill from a mad dog bite?" , "Extremely fanatical" , "Affected by 24 across" .)