Approaches caves and bats (8)
I believe the answer is:
advances
'approaches' is the definition.
('advance' can be a synonym of 'approach')
'caves and bats' is the wordplay.
'bats' indicates anagramming the letters (slang for mad).
'caves'+'and'='cavesand'
'cavesand' with letters rearranged gives 'ADVANCES'.
(Other definitions for advances that I've seen before include "Amounts paid before they're earned" , "Progresses" , "Improvements; moves forwards" , "Forward movements" , "Moves forwards in a purposeful way" .)