Fancy cities mostly find Conservative to be methodical (10)
I believe the answer is:
scientific
'be methodical' is the definition.
(thesaurus)
'fancy cities mostly find conservative' is the wordplay.
'fancy' indicates an anagram.
'mostly' means to remove the last letter.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'find' with its final letter taken away is 'fin'.
'cities'+'fin'='citiesfin'
'citiesfin' with letters rearranged gives 'scientifi'.
'scientifi'+'c'='SCIENTIFIC'
'to' is the link.
(Other definitions for scientific that I've seen before include "Systematic; methodical" , "using what's proven" , "Trained in biology, perhaps" , "As experiment" , "Based on observation" .)