Detailed, penetrating (2,5)
I believe the answer is:
in depth
This clue is a double definition.
'detailed' is the first definition.
(I've seen this before)
'penetrating' is the second definition.
(I've seen this before)
(Other definitions for in depth that I've seen before include "Penetrating" , "Not 16 [SHALLOW], anyway" , "comprehensive" , "Detailed sort of investigation" , "Thoroughly and comprehensively" .)