Loco dabbler? (7)

I believe the answer is:

mallard

I believe this is a double definition.

'loco' is the first definition.
(Mallard is a type of locomotive)

'dabbler?' is the second definition.
(mallard ducks dabble in order to feed)

(Other definitions for mallard that I've seen before include "Oldest breed of duck" , "Type of duck - world speed record holding steam engine (1938)" , "Common wild duck" , "The famous steam train" , "Engine holding the world speed record for a steam locomotive, set at 123mph in 1938" .)

I've seen this clue in The Times.

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