It could take us to Birkenhead (3)
I believe the answer is:
bus
'it could' is the definition.
The definition suggests a singular noun which matches the answer.
'us to birkenhead' is the wordplay.
'to' means one lot of letters go next to another (I've seen this in other clues).
'birkenhead' becomes 'b' (head letter of 'birken').
'us' put after 'b' is 'BUS'.
'take' acts as a link.
Can you help me to learn more?
(Other definitions for bus that I've seen before include "Public service vehicle" , "Use transport" , "Means of public transport" , "Coach" , "People carrier" .)