Bow has only one old bus station? (4)
I believe the answer is:
stop
'bus station?' is the definition.
(I've seen this in another clue)
'bow has only one old' is the wordplay.
I cannot quite understand how this works, but
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is present in the answer.
The remaining letters 'stp' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for stop that I've seen before include "Cease, desist, whoa" , "Cease, halt" , "Check" , "cut out" , "Bung" .)