Blacklegs providing taxis at the transport centre (5)
I believe the answer is:
scabs
'blacklegs' is the definition.
('scab' can be a synonym of 'blackleg')
'taxis at the transport centre' is the wordplay.
'taxis' becomes 'cabs' ('cab' can be a synonym of 'taxi').
'at' means one lot of letters go next to another (I've seen this in other clues).
'centre' indicates the central letters.
The centre of 'transport' is 's'.
'cabs' after 's' is 'SCABS'.
'providing' is the link.
(Other definitions for scabs that I've seen before include "They continue to work" , "Wound crusts" , "Blacklegs, strikebreakers" .)