The most common and most likely answer to this crossword clue is the 13 letter word ABBREVIATIONS
A
B
B
R
E
V
I
A
T
I
O
N
S
Buddy explains!
The straight part
We know that "USA and USSR perhaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case usa and ussr perhaps = abbreviations.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ABBREVIATIONS mean?
ABBREVIATIONS noun- The result of shortening or reducing; abridgment.
- A shortened or contracted form of a word or phrase, used to represent the whole, utilizing omission of letters, and sometimes substitution of letters, or duplication of initial letters to signify plurality, including signs such as +, =, @.
- The process of abbreviating.
- A notation used in music score to denote a direction, as pp or mf.
- One or more dashes through the stem of a note, dividing it respectively into quavers, semiquavers, demisemiquavers, or hemidemisemiquavers.
- Any convenient short form used as a substitution for an understood or inferred whole.
- Loss during evolution of the final stages of the ancestral ontogenetic pattern.
- Reduction to lower terms, as a fraction.