The pair Cleo contrives to hold up (6)
I believe the answer is:
couple
'the pair' is the definition.
(couple is a kind of pair)
'cleo contrives to hold up' is the wordplay.
'contrives' is an anagram indicator.
'to hold' indicates putting letters inside.
'cleo' anagrammed gives 'cole'.
'cole' enclosing 'up' is 'COUPLE'.
(Other definitions for couple that I've seen before include "Married pair; two forces causing rotation" , "Bonnie and Clyde, say" , "Pair, duo" , "Twosome" , "Pair - put together" .)