Dubious American power dissenting body welcomes (7)
I believe the answer is:
suspect
'dubious' is the definition.
(I've seen this before)
'american power dissenting body welcomes' is the wordplay.
'american' becomes 'US' (United States).
'power' becomes 'p' (symbol in physics).
'dissenting body' becomes 'sect' (I've seen this in another clue).
'welcomes' indicates putting letters inside.
'us'+'p'='usp'
'usp' placed inside 'sect' is 'SUSPECT'.
(Other definitions for suspect that I've seen before include "Imagine to be guilty" , "Doubt truth of" , "Consider or believe likely" , "Possibly dangerous or false" , "Doubt; mistrust" .)