Two very common verbs cause no trouble (6)

I believe the answer is:

behave

'cause no trouble' is the definition.
(to be no trouble is to behave well)

I cannot understand how the rest of the clue works.

(Other definitions for behave that I've seen before include "Stop acting up!" , "function" , "Act appropriately" , "Act properly" , "Conduct oneself properly" .)

I've seen this clue in The Times.

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