Continues to hold this one back (4)
I believe the answer is:
unit
'continues to hold this one back' is the definition.
'unit' can be an answer for 'one' (synonyms). I'm not sure about the remainder of the definition.
'continues to hold this one back' is the wordplay.
'to hold' says the answer is hidden in the clue (I've seen 'holding' mean this).
'this one back' is a reversal indicator.
'tinu' is hidden within 'continues'.
'tinu' in reverse letter order is 'UNIT'.
Can you help me to learn more?
(Other definitions for unit that I've seen before include "Building block - small military force" , "Individual thing; one" , "Whole - group" , "Single undivided whole" , "Mexican maize pancake" .)