Time reckless fellow permitted one of three (7)
I believe the answer is:
triplet
'one of three' is the definition.
(one of a set of triplets)
'time reckless fellow permitted' is the wordplay.
'time' becomes 't' (abbreviation).
'reckless fellow' becomes 'rip' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'permitted' becomes 'let' (to let something happen is to permit it).
't'+'rip'+'let'='TRIPLET'
Can you help me to learn more?
(Other definitions for triplet that I've seen before include "One of a set of three" , "Handful of notes" , "One of three at the same birth" , "One of a small group" , "sibling?" .)