Not getting one's leg over a bicycle in motion (8)
I believe the answer is:
celibacy
'not getting one's leg' is the definition.
I can't tell whether this definition defines the answer.
'over a bicycle in motion' is the wordplay.
'over' is an insertion indicator.
'in motion' is an anagram indicator (I've seen this in other clues).
'bicycle' is an anagram of 'celibcy'.
'a' going inside 'celibcy' is 'CELIBACY'.
Can you help me to learn more?
(Other definitions for celibacy that I've seen before include "Chastity" , "Unmarried state on a bicycle" , "requirement for RC priest" , "nothing personal!" , "Abstention from the other" .)