The most common and most likely answer to this crossword clue is the 5 letter word POLYP
I've seen this crossword clue in The Guardian
P
O
L
Y
P
More clues leading to the result POLYP
- Party leader pursues old educational institution’s growth
- It could be a sea anemone, parrot said softly
- Pressure put on old college showing little growth
- Growth of power with steel tower mostly erected
- Growth allows old-style educational institution to gain power
- Held back by lumpy, lopsided growth
- The animal that emerges from monopoly players
- Former university with pressure for growth
- Growth in borders of poppy crop returned
- Growth of college power
Buddy explains!

The straight part
We know that "growth" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case growth = polyp.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 POLYP mean?
POLYP noun- An abnormal growth protruding from a mucous membrane
- A cylindrical coelenterate, such as the hydra, having a mouth surrounded with tentacles