Crossword Genius

Pulse is fast - over one fifty (6)

Ross

I believe the answer is:

lentil

'pulse' is the definition.
(thesaurus)

'fast over one fifty' is the wordplay.
'fast' becomes 'lent' (I've seen this before).
'over' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'fifty' becomes 'l' (roman numeral).
'lent'+'i'+'l'='LENTIL'

'is' acts as a link.

(Other definitions for lentil that I've seen before include "Lintel (anag.)" , "Edible seed of bean plant" , "Pulse for soup etc" , "'Seed, pulse (6)'" , "Small edible seed" .)

I've seen this clue in The Telegraph.
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