Irish lady, criminal and policeman seek precious gems (8)
I believe the answer is:
emeralds
'gems' is the definition.
(emerald is a kind of gem)
'irish lady criminal and policeman seek precious' is the wordplay.
I cannot quite see how this works, but
'lady' could be 'emera' and 'emera' is present in the answer.
'policeman' could be 'ds' (abbreviation for Detective Sergeant) and 'ds' is present in the answer.
A single letter 'l' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for emeralds that I've seen before include "Mere lads (anag.)" , "Green stones from strangely red males" , "Green gems" , "Colours" , "They're preciously green on the Isle" .)