I’m obliged to weed lake (5)

I believe the answer is:

tahoe

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'lake' is the definition.
(Lake Tahoe in the USA)

'i'm obliged to weed' is the wordplay.
'i'm obliged' becomes 'ta' (I can't justify this - if you can you should give a lot more credence to this answer).
'to weed' becomes 'hoe' (I've seen this before).
'ta'+'hoe'='TAHOE'

Can you help me to learn more?

(Other definitions for tahoe that I've seen before include "Mountain lake" , "Lake in Sierra Nevada mountains" , "US lake" , "Nevada/California lake" , "Lake/desert resort on the California-Nevada border" .)

I've seen this clue in The Times.

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