Pearl madly involves us in study (7)
I believe the answer is:
perusal
'study' is the definition.
(thesaurus)
'pearl madly involves us' is the wordplay.
'madly' indicates an anagram.
'involves' indicates putting letters inside.
'pearl' with letters rearranged gives 'peral'.
'peral' enclosing 'us' is 'PERUSAL'.
'in' is the link.
(Other definitions for perusal that I've seen before include "Thorough reading" , "Process of examination" , "thorough scan" , "Scanning, reading" , "A casual read or study" .)