Considers criminal person holds diamonds (7)
I believe the answer is:
ponders
'considers' is the definition.
(to ponder something is to consider it)
'criminal person holds diamonds' is the wordplay.
'criminal' indicates anagramming the letters.
'holds' is an insertion indicator.
'diamonds' becomes 'd' (abbreviation in bridge say).
'person' anagrammed gives 'poners'.
'poners' placed around 'd' is 'PONDERS'.
(Other definitions for ponders that I've seen before include "Ruminates" , "Engages in meditation" .)