Many cross about pound gratuity (8)
I believe the answer is:
multiple
'many' is the definition.
(similar in meaning)
'cross about pound gratuity' is the wordplay.
'cross' becomes 'mule' (I've seen this before).
'about' indicates putting letters inside.
'pound' becomes 'L' (the pound sign is based on an L).
'gratuity' becomes 'tip' (synonyms).
'l'+'tip'='ltip'
'mule' placed around 'ltip' is 'MULTIPLE'.
(Other definitions for multiple that I've seen before include "Manifold; numerous" , "Lit plume (anag)" , "Having many parts or components" , "Numerous and often varied" , "Having or involving many parts" .)