Local shot in the arm with stimulant (4)

I believe the answer is:

spur

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'stimulant' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

(Other definitions for spur that I've seen before include "Device to urge on a horse" , "Incentive; branch line" , "Goad as for a horse" , "footballer?" , "railway siding" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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