Itty bit (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
iota
'itty bit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for iota that I've seen before include "Trace" , "Greek equivalent of the letter I" , "Jot, particle" , "Smidgeon" , "Tiny piece" .)