Unit of distance? More like temperature, surprisingly (9)
I believe the answer is:
kilometre
'unit of distance?' is the definition.
(I've seen this before)
'more like temperature surprisingly' is the wordplay.
'temperature' becomes 't' (abbreviation).
'surprisingly' indicates anagramming the letters (a surprising ordering of the letters).
'more'+'like'+'t'='moreliket'
'moreliket' is an anagram of 'KILOMETRE'.
(Other definitions for kilometre that I've seen before include "1000m" , "0.621 of a mile" , "Measure of distance" , "5/8ths of a mile" , "K stands for this" .)