Second eleven to provide driving force (5)

I believe the answer is:

steam

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'driving force' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for steam that I've seen before include "Gas from boiliing water" , "enthusiasm" , "Vapour from water at boiling point" , "Vaporous exhalation" , "Invisible gas from boiling water" .)

I've seen this clue in The Sun and the Financial Times.

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