Clever to take in mineral and cordial (8)
I believe the answer is:
amicable
'cordial' is the definition.
(I've seen this before)
'clever to take in mineral' is the wordplay.
'clever' becomes 'able' (I've seen this before).
'to take in' means one lot of letters goes inside another.
'mineral' becomes 'mica' (mica is a kind of mineral).
'able' enclosing 'mica' is 'AMICABLE'.
'and' is the link.
(Other definitions for amicable that I've seen before include "Friendly, good-humoured" , "Friendly, reasonable" , "sweet?" , "Friendly, nonthreatening" , "Friendly and good-tempered" .)