Last in bar, I check bolt (5)
I believe the answer is:
rivet
'bolt' is the definition.
(thesaurus)
'last in bar i check' is the wordplay.
'last in' says to take the final letters.
'check' becomes 'vet' (I've seen this before).
The final letter of 'bar' is 'r'.
'r'+'i'+'vet'='RIVET'
(Other definitions for rivet that I've seen before include "Bolt in iron" , "Metal fastening pin" , "Fascinate" , "Clinch - bolt" , "Fasten -- engross" .)