Think of Americans (5)
I believe the answer is:
guess
This clue might be a double definition.
'think' is the first definition.
(synonyms)
'of americans' is the second definition.
The definition suggests a singular noun which matches the answer.
Can you help me to learn more?
(Other definitions for guess that I've seen before include "Hypothesis" , "Conjecture - estimate" , "Estimate; suppose" , "Estimate on the basis of little information" , "Divine - estimate" .)