Dotty loves crack (5)
I believe the answer is:
solve
'crack' is the definition.
(crack can mean to solve or decipher)
'dotty loves' is the wordplay.
'dotty' indicates anagramming the letters (a mad or 'dotty' version of the letters).
'loves' anagrammed gives 'SOLVE'.
(Other definitions for solve that I've seen before include "Figure out the answer" , "Find the answer or explanation" , "Settle" , "Voles (anag.)" , "Find the solution to puzzle or problem" .)