Communist right to reject books mentioning Methuselah (4)
I believe the answer is:
trot
'communist' is the definition.
(short for Trotskyist)
'right to reject books mentioning methuselah' is the wordplay.
I cannot quite understand how this works, but
'right' could be 'r' (common abbreviation) and 'r' is present in the answer.
'to' is found in the answer.
A single letter 't' remains 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 trot that I've seen before include "Red" , "Horse's gait - extreme leftist" , "Left-winger - move at a fair speed" , "Run at moderate pace" , "Run (like a horse)" .)