Rehearsed an act in "The Spider Web" (9)
I believe the answer is:
practised
'rehearsed an' is the definition.
'practised' can be an answer for 'rehearsed' ('practise' can be a synonym of 'rehearse'). I am not certain of the 'an' bit.
'act in the spider web' is the wordplay.
'in the' is an insertion indicator.
'spider web' becomes 'prised' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'act' inserted into 'prised' is 'PRACTISED'.
Can you help me to learn more?
(Other definitions for practised that I've seen before include "Expert" , "Learned by repetition" , "Carried out or rehearsed" .)