Minute: parts of it covering years and years (4-5)
I believe the answer is:
itsy-bitsy
'minute' is the definition.
(thesaurus)
'parts of it covering years and years' is the wordplay.
I cannot really understand how this works, but
'parts' could be 'bits' (bit is a kind of part) and 'bits' is found in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found within the answer.
'years' could be 'yy' (an abbreviation for year written twice) and 'yy' is found within the remaining letters.
The remaining letters 'is' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for itsy-bitsy that I've seen before include "Teensy-weensy" , "Very little" , "Very small, tiny" , "Teeny-weeny" .)