Selfish fan reined in a cost (13)
I believe the answer is:
inconsiderate
'selfish' is the definition.
(associated in meaning)
'fan reined in a cost' is the wordplay.
'fan' is an anagram indicator (letters must be fanned around).
'reined'+'in'+'a'+'cost'='reinedinacost'
'reinedinacost' with letters rearranged gives 'INCONSIDERATE'.
(Other definitions for inconsiderate that I've seen before include "Unkind" , "Selfish" , "Without regard for the feelings of others" , "Self-centred" , "Uncaring" .)