Come back together, finding Roger terribly informed (7)
I believe the answer is:
regroup
'come back together' is the definition.
I can't judge whether this definition defines the answer.
'roger terribly informed' is the wordplay.
'terribly' is an anagram indicator.
'informed' becomes 'up' (being up on a topic means being informed about it).
'roger' anagrammed gives 'regro'.
'regro'+'up'='REGROUP'
'finding' acts as a link.
Can you help me to learn more?
(Other definitions for regroup that I've seen before include "form new parties" , "make new arrangements" , "Consider new tactics after a setback" , "Organise again after a defeat" , "Get together again after being defeated" .)