Prison meal served up cold (10)
I believe the answer is:
impersonal
'cold' is the definition.
(similar in meaning)
'prison meal served up' is the wordplay.
'served up' indicates anagramming the letters.
'prison'+'meal'='prisonmeal'
'prisonmeal' is an anagram of 'IMPERSONAL'.
(Other definitions for impersonal that I've seen before include "Objective; disinterested" , "Aloof" , "Ignoring one's own feelings" , "Cold" , "Cool" .)