Lose it down a gutter, its front blocking gondola (4,1,6)

I believe the answer is:
blow a gasket
'lose it' is the definition.
(I've seen this in another clue)
'down a gutter its front blocking gondola' is the wordplay.
I cannot quite see how this works, but
'down' could be 'low' (similar in meaning) and 'low' is found within the answer.
'a' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
I've seen this clue in The Times.
Want a hint initially instead of a full solution?
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