Concentrated on joining fellow circus act (9)
I believe the answer is:
strongman
'circus act' is the definition.
The definition suggests a singular noun which matches the answer.
'concentrated on joining fellow' is the wordplay.
'concentrated on' becomes 'strong' (I've seen this in another clue. I am not sure about the 'on' bit.).
'joining' says to put letters next to each other.
'fellow' becomes 'man' (fellow can mean a man).
'strong'+'man'='STRONGMAN'
Can you help me to learn more?
(Other definitions for strongman that I've seen before include "power shower" , "Powerful politician" .)