Film about when rugby official's becoming most distant — at three o'clock? (8)
I believe the answer is:
eastmost
'official's becoming most distant at three o'clock?' is the definition.
I can't judge whether this definition defines the answer.
'film about when rugby' is the wordplay.
'film' becomes 'ET' (E.T. the Extra-Terrestrial).
'about' is an insertion indicator.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'rugby' becomes 'most' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'et' enclosing 'as' is 'east'.
'east'+'most'='EASTMOST'
Can you help me to learn more?
(Another definition for eastmost that I've seen is " Furthest to the Orient".)