Review power plant being erected (5)
I believe the answer is:
recap
'review' is the definition.
(I know that review can be written as recap)
'power plant being erected' is the wordplay.
'power' becomes 'p' (symbol in physics).
'plant being' becomes 'acer' (I am not sure about this - if you are sure you should believe this answer much more).
'erected' is a reversal indicator (in a down clue, letters go up).
'p'+'acer'='pacer'
'pacer' reversed gives 'RECAP'.
Can you help me to learn more?
(Other definitions for recap that I've seen before include "Reiterate" , "Summary (abbr.)" , "Run over the points again" , "Summarise at the end" , "go over chief points again" .)