Rescue riveter working on base of bridge (8)
I believe the answer is:
retrieve
'rescue' is the definition.
(I've seen this before)
'riveter working on base of bridge' is the wordplay.
'working' indicates anagramming the letters.
'on' indicates putting letters inside (as in clothing \'on\' a person).
'base of' indicates one should take the final letters.
The final letter of 'bridge' is 'e'.
'riveter' anagrammed gives 'retrive'.
'retrive' placed around 'e' is 'RETRIEVE'.
(Other definitions for retrieve that I've seen before include "Revere it to get back" , "Find and bring back" , "Rescue" , "Recover" , "(Of dog) fetch shot game" .)