Long seat in church aisle needing length (6)
I believe the answer is:
chaise
'long seat' is the definition.
(I've seen this in another clue)
'church aisle needing length' is the wordplay.
I cannot really see how this works, but
'church' could be 'ch' (abbreviation on maps etc) and 'ch' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for chaise that I've seen before include "... longue, chair for reclining" , "Light open carriage" .)