Pint he’d prepared, being thorough (2-5)
I believe the answer is:
in-depth
'thorough' is the definition.
(I've seen this before)
'pint hed prepared' is the subsidiary indication.
'prepared' indicates an anagram.
'pint'+'hed'='pinthed'
'pinthed' is an anagram of 'indepth'.
'being' is the link.
(Other definitions for in-depth that I've seen before include "Getting to the bottom of it" , "Profoundly (studied)" , "Comprehensive and thorough" , "Thoroughly and comprehensively" , "With thorough and extensive investigation" .)