Lever in line with first of beams joining wheels (7)
I believe the answer is:
crowbar
'lever' is the definition.
(I know that crowbar is a type of lever)
'line with first of beams joining wheels' is the wordplay.
'line' becomes 'row' (a row or line of things).
'with' means one lot of letters go next to another.
'first of' suggests taking the first letters.
'joining' means one lot of letters goes inside another (inserted letters join the word).
'wheels' becomes 'car' (wheels can informally mean a car).
The initial letter of 'beams' is 'b'.
'row'+'b'='rowb'
'rowb' inserted into 'car' is 'CROWBAR'.
'in' is the link.
(Other definitions for crowbar that I've seen before include "Heavy iron lever" , "Tool for breaking and entering" , "Purchase may be obtained from this" , "Metal rod used as a lever" , "that can exert powerful leverage" .)