Be opposite to but somehow inside ship (7)

I believe the answer is:

subtend

'be opposite to' is the definition.
(subtending is a kind of being opposite to)

'but somehow inside ship' is the wordplay.
'somehow' indicates anagramming the letters.
'inside' is an insertion indicator.
'ship' becomes 'send' (synonyms).
'but' is an anagram of 'ubt'.
'ubt' placed inside 'send' is 'SUBTEND'.

(Another definition for subtend that I've seen is " (Of line) form (angle) at a point where lines from its ends meet".)

I've seen this clue in The Times.

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