Prime Minister Boris throws knight out of booth, carelessly ruining picture (9)
I believe the answer is:
photobomb
'carelessly ruining picture' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'prime minister boris throws knight out of booth' is the wordplay.
I cannot quite understand how this works, but
'of' could be 'o' and 'o' is found within the answer.
an anagram of 'booth' is 'htobo' which is within the remaining letters.
'minister' could be 'pm' (PM is an example) and 'pm' is found in the leftover letters.
A single letter 'b' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?