Working party, caught by surprise, waste time (10)

I believe the answer is:

boondoggle

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'waste time' is the definition.
Although both the answer and definition are verbs in their base form, I don't understand how they can define each other.

'working party caught by surprise' is the wordplay.
'working' becomes 'on' (on can mean working or activated).
'party' becomes 'do' (do is a kind of party).
'caught by' indicates putting letters inside.
'surprise' becomes 'boggle' (boggling is a kind of surprising).
'on'+'do'='ondo'
'ondo' placed inside 'boggle' is 'BOONDOGGLE'.

Can you help me to learn more?

(Other definitions for boondoggle that I've seen before include "Unnecessary or wasteful project (US)" , "work without benefit in the US" .)

I've seen this clue in The Sunday Times and The Times.

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